Locator and tracking service for peer to peer resources

ABSTRACT

A resource naming service (RNS) server receives peer resource requests from peer platforms through a networking environment. The RNS server, possibly in cooperation with other RNS servers and peer registrars generates a response to the request to enable the peer platforms to access the requested peer resources. In one embodiment, a response includes a list of locations of peer devices in the networking environment where a resource is expected to be available. A requesting device can then choose to access the resource from one or more of the listed peer locations.

RELATED APPLICATIONS

The application claims priority to provisional patent application No.60/252,658, titled, “A Locator and Tracking Service for Peer-to-PeerResources,” filed Nov. 22, 2000, and provisional patent application No.60/252,659, titled “A Universal Naming Scheme for Peer-to-PeerResources,” also filed Nov. 22, 2000, both of which are herebyincorporated by reference.

This application is related to U.S. application Ser. No. 09/952,808,filed on Sep. 13, 2001, titled “Universal Naming Scheme for Peer to PeerResources”.

This application is related to U.S. application Ser. No. 09/952,367,filed on Sep. 13, 2001, titled “Resource Coherency among ResourcesCached in a Peer to Peer Environment”.

FIELD OF THE INVENTION

The present invention pertains to the field of networking. Moreparticularly, this invention relates to peer-to-peer networking.

BACKGROUND

Data networks are based on “client-server” interactions. Serversprovide, or serve, access to various network resources. Clients requestaccess to the resources from the servers. An Internet Service Provider(ISP) is one example of a server. Clients request access to the Internetfrom the ISP and the ISP provides access. Once a client has access tothe Internet through the ISP, the client may request access to avirtually endless variety of additional resources provided by millionsof different servers on the Internet.

In a traditional client-server environment, resources are oftenconcentrated in a relatively small number of centralized servers thatservice requests from a much larger number of clients. Concentratingresources on a few servers in this traditional approach has itsdrawbacks. For instance, the servers need to run on very fast machinesthat can process large volumes of client requests. A server machine anda network connection that can handle simultaneous transactions withthousands, or even millions, of clients is likely to be very expensiveto purchase and maintain.

Furthermore, during times of exceptionally high network traffic, eventhe fastest centralized servers can become bottlenecks in the network.For instance, as a nationwide news story breaks, the amount of time ittakes to access the latest updates at most news websites tends toincrease dramatically due to the increased network traffic. Moreover, ifone of these large-scale centralized machines fails for any reason,millions of clients will be denied access to the desired resource. Thisvulnerability makes centralized servers prime targets for hackers andcyber-terrorists.

A less traditional approach to networking is based on peer-to-peerinteractions. In a peer-to-peer environment, transactions take placebetween end-user, or peer, machines. Each peer can be both a consumerand a provider of resources. That is, a peer can act like a traditionalclient by requesting access to a resource stored elsewhere, and the samepeer can also act like a traditional server by responding to a requestfor a resource stored at the peer.

Peer-to-peer networking theoretically has a number of advantages overthe traditional approach. Rather than funneling huge volumes of clienttransactions to centralized servers, multiple peers can work together toreplace entire servers. For instance, if a resource is copied and cachedon many peer machines, a request for the resource can be serviced by anyone of the peers, or even by several of these peers at the same time, byhaving each of the multiple peers only serve a portion of the resource,in order to maximize the aggregate download bandwidth for the resource.By spreading resources out over multiple peers, bottlenecks atcentralized servers can be reduced. Also, end-user peer machines tend tobe comparatively inexpensive and are already present in most networkingenvironments. Using the available, cumulative processing power andavailable bandwidth of peer machines can substantially decrease theoverall cost of a network by reducing the number of expensive,centralized servers.

An additional benefit of a peer-to-peer networking approach is thefrictionless publishing of content. Given that in a peer-to-peer system,every peer machine can be both a consumer and a publisher ofinformation, publishing information in such a system can be as easy ascreating a new file. This completely eliminates the friction involvedwith publishing content in a client-server environment (such as, forinstance, the steps involved in publishing on a corporate Intranetportal), and thus encourages users to share more content with eachother. This type of sharing is especially relevant in an Intranetcontext that is made up of “islands of information” (such as userdesktops and laptops) that contain up-to-date, enterprise-criticalinformation that is normally never shared by users.

Unfortunately, most traditional approaches to managing network trafficand resources do not conveniently accommodate peer-to-peer networking.For instance, locating servers on the World Wide Web relies on theDomain Name System (DNS). DNS is a well-established hierarchical schemeused for naming Internet hosts, or servers. DNS was designed to resolvehost names to Internet Protocol (IP) addresses. That is, DNS resolvesthe host name part of URLs that are meaningful to humans, such aswww.USnews.com, to IP addresses that are meaningful to Internet routersand switches, such as 205.245.172.72. The IP address and related hostname of a given host machine are propagated to various DNS serversthroughout the Internet so that client requests made using the host'sname (such as requesting a URL containing that particular host name) areappropriately routed to the correct IP address. Propagating or updatingthis information can take a comparatively long period of time, on theorder of several hours or even days.

DNS works well for locating network resources that are all available atone particular host, and for hosts that have relatively static IPaddresses.

Peers, however, often have dynamically allocated IP addresses. That is,each time a peer logs onto the Internet, the peer is likely to have adifferent IP address. For instance, a corporate user may alternativelyconnect their laptop to the Internet from the office or from home, usingtwo different IP addresses, none of which may be statically assigned(assuming both the enterprise and the ISP use Dynamic Host ConfigurationProtocol (DHCP) for assigning host addresses). It is not uncommon forthe duration between peer log-ons to be shorter than the time periodneeded to propagate a new IP address through the DNS system. In whichcase, most of the time, it would not be possible or not reliable to finda peer by using its DNS host name.

Furthermore, a peer-to-peer resource that has been copied and cached maybe simultaneously available at many locations. In a corporate Intranetenvironment, this could be the case for a marketing report that isaccessed by several users. Caching resources is advantageous for anumber of reasons. Firstly, it promotes availability of resources. Forinstance, if resources published from a laptop are systematically cachedon an enterprise server, these resources will continue to be availableafter the publisher closes their laptop and leaves for the day.Secondly, caching allows resources to be kept “closer” (in terms ofnetwork topology) to where they are used. For instance, in ageographically distributed enterprise it may be advantageous to cache“hot” documents in each office location, to provide better responsetimes when accessing those documents.

As new versions of the resource are created however, old copies of theresource stored on other peers become outdated, and should beinvalidated (i.e. not used any longer) as the new version propagatesamong the peers. This illustrates another shortcoming of DNS, itsinability (due to a lack of a fine-enough granularity) to keep track ofindividual resources, and to track resources that can be available atmultiple locations, locations having dynamically changing IP addresses,and locations that potentially store different versions of the sameresource.

Furthermore, in the presence of multiple peer copies for the sameresource, it is important to be able to select a small set of “best”, or“closest”, copies for a given request. This ability requires tracking ofall equivalent peer locations that have an up-to-date copy of and canserve the cached resource.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the present invention are illustrated in the accompanyingdrawings. The accompanying drawings, however, do not limit the scope ofthe present invention. Similar references in the drawings indicatesimilar elements.

FIG. 1 illustrates one embodiment of a peer-to-peer realm.

FIG. 2 demonstrates one embodiment of locating a peer resource from theperspective of an RNS server.

FIG. 3 illustrates one embodiment of a peer.

FIG. 4 demonstrates one embodiment of locating a peer resource from theperspective of the peer platform shown in FIG. 3.

FIG. 5 demonstrates one embodiment of a cache coherency scheme.

FIG. 6 demonstrates one embodiment of resolving a peer resource address.

FIG. 7 illustrates one embodiment of a hardware system to perform thepresent invention.

FIG. 8 illustrates one embodiment of a machine readable storage mediumto store machine readable instructions of the present invention.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. However, those skilled in the art will understand that thepresent invention may be practiced without these specific details, thatthe present invention is not limited to the depicted embodiments, andthat the present invention may be practiced in a variety of alternateembodiments. In other instances, well known methods, procedures,components, and circuits have not been described in detail.

Parts of the description will be presented using terminology commonlyemployed by those skilled in the art to convey the substance of theirwork to others skilled in the art. Also, parts of the description willbe presented in terms of operations performed through the execution ofprogramming instructions. As well understood by those skilled in theart, these operations often take the form of electrical, magnetic, oroptical signals capable of being stored, transferred, combined, andotherwise manipulated through, for instance, electrical components.

Various operations will be described as multiple discrete stepsperformed in turn in a manner that is helpful in understanding thepresent invention. However, the order of description should not beconstrued as to imply that these operations are necessarily performed inthe order they are presented, or even order dependent. Lastly, repeatedusage of the phrase “in one embodiment” does not necessarily refer tothe same embodiment, although it may.

Overview

A number of inventions are described below with respect to a ResourceNaming Service (RNS) that is used to track and locate resources amongpeers in a peer-to-peer networking environment. RNS relies on a resourcenaming scheme that uniquely identifies peer resources no matter whereamong the peers the resources may currently be available. RNS overcomesthe inadequacies of existing networking schemes, such as the Domain NameSystem (DNS) based naming, making it possible to take full advantage ofthe power of peer-to-peer networking.

FIG. 1 illustrates one embodiment of the inventive peer-to-peer network.In the illustrated embodiment, peer-to-peer realm 150 (hereafter simplycalled “realm”) includes registrar 110, gate server 120, a number of RNSservers 130, and a number of peers 140. Peers 140 store, or otherwisemake available, peer resources (not shown). Registrar 110, RNS servers130, and gate server 120 together provide a locator and access servicefor tracking, locating, and accessing the peer resources published inthe realm. While one each of the registrar and gate server, and severalRNS servers and peers are shown in FIG. 1, the present invention may bepracticed with any number of these elements.

To participate in the realm, each peer 140 first registers withregistrar 110. As part of the registration process, registrar 110assigns each peer an identifier that is unique within realm 150, andalso assigns each peer to a particular RNS server 130, hereafter calledthe “home RNS server” for that peer. The unique identifier for a givenpeer 140 is used to identify peer resources within realm 150 that areunder the control of, or published by, the peer.

Any number of approaches can be used to register peers 140 withregistrar 110. In one embodiment, peers 140 may use a Web-basedregistration process to obtain and register an identity with registrar110. Registration may comprise a series of interactions between a peer140 and registrar 110 to convey a user's identity, encryption keys forsecure communications among elements within realm 150, billinginformation for access various peer resources, downloading andinstalling software to enable the peer 140 to be compatible with itsassigned RNS server, and the like.

Any number of approaches can also be used by registrar 110 to select ahome RNS servers for a particular peer 140. In one embodiment, registrar110 identifies the type, or version, of software that the peer 140 isusing, and generates a list of RNS server 130 that are compatible withthat software and that are estimated by registrar 110 to be “close” tothe registering peer 140 in terms of network topology. Then, registrar110 provides this list of candidate RNS servers to the peer 140 so thatthe peer 140 can test the network paths to each listed RNS server andidentify one or more that have the best response times. That is,depending on network topology, the peer 140 is likely to be “closer” tosome RNS servers than others, either by physical distance or by thespeed of the network medium. In one embodiment, the peer's selection isreturned to registrar 110 merely as a suggestion. That is, registrar 110may or may not assign the peer 140 to the RNS server 130 that the peerselected depending on factors such as the relative network traffic loadsamong the list of candidate RNS servers. In which case, registrar 110may only assign the suggested RNS server to be the home RNS server forthe peer 140 if the suggested RNS server's relative network traffic loadis below a particular level. Otherwise, the registrar may assign adifferent RNS server having, for instance, a lowest relative networktraffic load among the candidate RNS servers.

Registrar 110 can also register new RNS servers in realm 150 using manyof the same techniques and reassign selected peers 140 to be homed atthe new RNS server. That is, in one embodiment, registrar 110 assigns aunique identifier for the RNS server, identifies a set of compatiblepeers 140, allows the new RNS server to suggest a set of preferredpeers, and then selects a set of peers to be homed at the new RNS serverbased on the suggestion as well as other factors. In alternateembodiments, any number of techniques can be used to register new RNSservers and assign peers. For instance, the new RNS server may simply beallowed to accumulate new peers over time as new peers register withregistrar 110.

Each RNS server 130 tracks the current network location (in terms of IPaddresses and IP port numbers) and status (on- or off-line) of all peersassigned to that RNS server, as well as the locations and availabilityof resources among its assigned peers.

In general, accessing a resource is a two step process. First, theresource must be located using the locator service. Second, the resourceis actually accessed at the location or set of locations returned by thelocator service.

For a peer 140 within realm 150, the first step in accessing a peerresource involves communicating with the peer's assigned home RNS server130. The home RNS server 130, possibly in cooperation with registrar 110and another RNS server 130, determines one or more locations withinrealm 150 where the resource is expected to be available. In oneembodiment, the set of locations returned by the home RNS server 130 tothe requesting peer 140 may depend on the current network identity (inparticular, the current IP address or IP addresses) of peer 140, on thecurrent traffic load on the realm, as well as on other parameters thatare known to the RNS servers 130. It is up to the peer 140 to take thesecond step to actually access the resource at the provided location(s).Once a peer has accessed a resource, it has the option to cache theresource, inform its home RNS server that it is now caching theresource, and make the cached resource available for other peers toaccess.

Client devices are considered to be outside realm 150 if they have notbeen endowed with the teachings of the current invention, or if theyhave not been registered with the registrar 110 of this realm 150. Suchdevices may be able to access information from the current realm 150,but will usually not be able to publish information in this realm.

For a client device outside realm 150, external network traffic 125 isdirected to realm 150 through gate server 120. Gate server 120, possiblyin cooperation with registrar 110 and one or more RNS servers 130,determines one or more peer locations 140 within realm 150 where theresource is expected to be available, in accordance to the resourcelocation process described above. Depending on whether the client deviceis compatible with the peer(s) hosting the resource, gate server 120 maysimply respond with the location(s) and allow the client device todirectly access the resource on its own. If the client device is notcompatible, gate server 120 may take any number of actions, such asaccessing the resource on behalf of the client device and responding asif the gate server were the resource.

As used herein, each resource is primarily associated with one peer,referred to as the master publisher, and may also be available atadditional peers, referred to as the caching publishers. Usually, only amaster publisher has the authority to publish, modify, or delete aresource.

The locating service presumes a resource addressing scheme that uniquelyidentifies the master publisher of a resource in the resource addressand includes a relative path for the resource with respect to the masterpublisher. The addressing scheme is unique, however, in that an addressdoes not necessarily direct a request to the master publisher itself,but instead to a resource locating service corresponding to the masterpublisher.

Using this “diverted” addressing scheme, the locating service can directa request to the master publisher as well as to any number of cachingpublishers. Even if the master publisher of the resource is not on-line,has crashed, is overwhelmed with other traffic, or is otherwise notimmediately available, the resource may still be persistently availablefrom a caching publisher. With potentially many peers caching resources,or with dedicated peers proactively caching resources, the locatorservice can persistently and reliably service huge volumes of requests.

The locator service can also track resources stored by peers havingdynamically changing addresses. For instance, in one embodiment, peers140 include machines that use modems to connect to the network throughan Internet Service Provider (ISP). Each time one of these peersconnects to the Internet, the ISP assigns it a new IP address using, forinstance, the Dynamic Host Configuration Protocol (DHCP). And, each timeone of these peers connects, the peer contacts its home RNS server tolet it know what its current IP address and port number are. The homeRNS server can then update any records it has for the peer with the newlocation. Then, while it is logged on, the peer periodically “pings” itshome RNS server to let the server know the peer is still logged on. Whenand if the pings stop, the home RNS server updates its records to showthat the location has become inactive. In alternate embodiments, anynumber of approaches could be used to track the current locations andavailability of transient and/or mobile peers.

Locating Resources

FIG. 2 illustrates one embodiment of locating a resource in more detail.The illustrated embodiment is from the perspective of an RNS server,although a gate server may perform similar functions. FIG. 2 includes anumber of implementation specific details. Other embodiments may notinclude all of the elements illustrated in FIG. 2, may perform elementsin a different order, and may include additional elements.

First, the RNS server 130 receives, from a peer 140 or from the gateserver 120, a resource request at 210 for the location of a particularresource. The request uniquely identifies a resource and a masterpublisher of the resource within the realm to which this RNS serverbelongs. The request can take any number of forms from a messagingprotocol specific to this particular locator service to a universallyaccepted protocol such as HTTP.

At 220, the RNS server checks its own memory to determine if it has aresource record corresponding to the requested resource. In oneembodiment, resource records comprise unique identifiers for resourcesand master publishers as well as one or more locations where theresources are expected to be located. The record may also indicatewhether or not particular locations are expected to be active (loggedinto the network or not). In which case, the RNS server compares theunique identifier from the request to the list of recorded uniqueidentifiers.

If the RNS server does have a matching record, the RNS server assumesthat the record is current. If the record lists an active location forthe resource, the RNS server responds in 230 with the resource statusand a set of locations. The record may list zero or more activelocations where the resource has been cached. If the record lists morethan one active location for the resource, the RNS server may respondwith multiple locations from which the requester can choose. Forsuccessive requests for the same resource, the RNS server may respondwith different sets of locations, selecting sets of locations in, forinstance, a round robin fashion, in order to balance the network trafficto multiple locations. In one embodiment, the RNS server may select thelocations to be returned in 230 based on the requester's network (IP)address, in order to provide the requester with addresses that are“proximal” in terms of network topology, and thus optimize networktraffic.

If the RNS server does not have a matching resource record, or if theRNS server has a matching resource record that does not actually listany active locations for the resource, the RNS server checks its memoryto determine if it has a publisher record for the publisher of therequested resource in 240. In one embodiment, publisher records compriseunique identifiers for master publishers as well as an identifier forthe home RNS server to which the master publisher was assigned. In whichcase, the RNS server compares the unique identifier from the request tothe list of recorded publisher identifiers.

If the RNS server does have a matching publisher record, the RNS serverassumes that the record is current and, in 250, determines whether ornot the master publisher is local. That is, the RNS server determineswhether or not it is the home RNS server for the master publisher.

If the master publisher is local, the RNS server obtains from the masterpublisher and caches (by creating an internal resource record) statusinformation for the resource in 260 and provides the resource statusinformation to the requester in 230. The status information couldinclude whether or not the master publisher is currently active (loggedin to the network or not) and whether or not the resource still exists.In order to determine whether or not a resource exists on an activemaster publisher, the RNS server queries the master publisher. If themaster publisher indicates that the resource exists, the RNS servercreates a record for the resource, including the location of thepublisher, and caches the record so that subsequent requests for theresource can be satisfied without communicating again with thepublisher.

The RNS server may know from its publisher record whether or not a localpublisher is active. For instance, in one embodiment, local publisherslog in to the RNS server each time they come on-line on the network, andthen “ping” the RNS server on a regular basis to let the RNS server knowthe local publisher is still active. In alternate embodiments, anynumber of approaches can be used to determine whether a master publisheris active, including a query from the RNS server, a publisher logoutprocedure, and the like.

If a local publisher is determined to be inactive, the RNS server canupdate any records it has associated with that publisher. That is, anyrecord for any resource that lists a particular publisher as a sourcecan be updated to show that the publisher is not active. Of course, ifthe resource does not exist and/or the master publisher of the resourceis inactive, the RNS server will return an appropriate error message in230.

If, in 250, the master publisher is not a local publisher, but the RNSserver discovered a publisher record in 240, the RNS server queries theremote RNS server (i.e. the assigned home RNS server for the masterpublisher) with an identifier of the master publisher and the resourceto obtain and cache (by creating a resource record) the statusinformation returned by the remote RNS server for the resource in 270.The remote RNS server may be able to immediately respond to the querybased on its own memory records. For instance, the remote RNS server mayhave records including additional active locations where the resource isexpected to be available. If the remote RNS server does not have arecord of any active locations for the resource, the remote RNS servermay be able to query the master publisher if the master publisher iscurrently active. Based on the response from the remote RNS server, thelocal RNS server provides a response in 230. Again, if the resource doesnot appear to exist, or if the resource is not currently available, theRNS server will respond accordingly. Also, the local RNS server willcache whatever it learns from the remote RNS so that future requests forthe resource can be serviced without resorting to the remote RNS. In oneembodiment, caching information about resources published by masterpublishers homed at a remote RNS server can be implemented on a leasingbasis, i.e. the cached information can be assumed to be valid for aspecified time after it was obtained from the remote RNS server;additional requests for cached information during that time can then beserviced without contacting the remote RNS server.

If, back in 240, the RNS server determines that it does not have apublisher record for the resource, the RNS server in 290 determines ifthe master publisher is a local publisher (i.e. if this is the home RNSfor the master publisher). If the master publisher is homed at this RNSserver, the algorithm continues to respond to the request at block 260as described above.

If at block 290 it is determined that the master publisher is not homedat this RNS server, the RNS server resorts to the registrar 110 in 280.The registrar 110 keeps records of each registered peer and the RNSserver to which each peer is assigned or homed at. From the registrar,the RNS server learns whether or not the publisher is registered, and,if so, to what RNS server the publisher has been assigned. Again, theRNS server caches (by creating a publisher record) the information toavoid contacting the registrar for future requests directed to the samemaster publisher.

Of course, if at 295 the publisher is not registered, there is no remoteRNS server to contact in 270, and the local RNS server will return theappropriate message in 230. If, however, the publisher is registered,the RNS server proceeds to contact the remote RNS server in 270 asdescribed above, and to respond to the request in block 230 accordingly.

As mentioned above, one embodiment of an RNS server tracks whether ornot peers homed at the RNS server are on- or off-line. The availabilityof peers can be tracked as part of the publisher records. For instance,a publisher record may be of the form:unique peer identifier: status/current IP address(es)/current portnumber(s)

In the illustrated embodiment, each time a peer logs in to its home RNSserver, the RNS server updates the peer's record to indicate that thepeer's status is on-line and records the peer's current IP address(es)and port number(s). When the peer is determined to have logged out, theRNS server again updates the peer's record to indicate that the peer'sstatus is off-line.

In alternate embodiments, an RNS server also tracks the status of peershomed at other RNS servers. For instance, status information for aremote RNS server can be cached along with current location informationon a leasing basis, such that the status information is presumed validfor a certain period of time.

By tracking the status of peers, an RNS server can persistently maintainresource records as the locations of peers change as, for instance,peers logout and log back in with a new IP addresses.

For example, a resource record entry may be of the form:unique resource identifier: master publisher identifier;publisher identifier₁; publisher identifier₂; publisher identifier₃; . ..

When the RNS server receives a request for the resource, the RNS serveridentifies the corresponding resource record entry based on the uniqueresource identifier and selects a set of publisher identifiers fromamong those listed. Then, the RNS server consults the publisher recordsto determine the current status of the corresponding publishers andreturns the current IP addresses and port numbers for each selectedpublisher who's status indicates that it is on-line.

In another embodiment, a resource record entry is of the form:unique resource identifier: IP₁, port₁; IP₂, port₂; IP₃, port₃; . . .

In this example, rather than listing the unique identifiers of thepublishers of the resource, the resource record lists actual networklocations for the resource. In which case, when the RNS server receivesa request for the resource, the RNS server selects from among the listedlocations and returns the selected locations without the intermediatestep of consulting the publisher records to determine which of theselected locations are expected to be on-line. In order to maintaincurrent locations for the publishers as their network locations change,the RNS server scans through the resource records and flags locationscorresponding to publishers that are determined to be off-line. When thepublishers log back in, the RNS server again scans through the resourcerecords, removes the flags, and replaces the old locations with thecurrent locations.

Of course, RNS servers can organize and utilize records in any number ofembodiments. For instance, the resource records and the publisherrecords may comprise one single list instead of two separate lists.Alternately, publisher records could be further divided into a list ofpeers assigned to the RNS server plus a separate list of peers assignedto other RNS servers. And, of course, a corresponding variety ofmechanisms and approaches can be used to track the current status ofpublishers and update publisher network locations.

Peer Platform

FIG. 3 illustrates one embodiment of a peer 140 from FIG. 1 in moredetail. Peer 140 includes peer platform 370, peer-to-peer application345, Web browser 365, and two persistent structures, publicationdirectory 380 and resource cache 385.

Peer-to-peer application 345 represents any of a variety of peer-to-peerapplications or Web services such as a distributed gaming applicationwhere every participant runs a copy of the game software. Browser 365represents any of a number of Web browsers, such as Netscape Navigator,Microsoft Internet Explorer, and the like. Persistent structures 380 and385 represent any of a variety of persistent memory devices such as harddisks, flash memory, or the like, addressed and organized in any of avariety of fashions. Other embodiments of peer 140 may includeadditional elements, may have elements arranged differently, and may notinclude all of the illustrated elements.

Peer platform 370 intercepts and directs all peer-to-peer traffic 320and resource locator traffic 310 for peer 140. Peer platform 370includes resource locator interface 330 to interface directly withlocator services, application programming interface (API) 340 tointerface with peer-to-peer application 345, server 350 to servepeer-to-peer requests 320 (described more fully below), and proxycomponent 360 to interface with web browser 365 and with peer-to-peerapplication 345. In one embodiment, peer platform 370 runs as anapplication on peer 140, using the operating system services of peer 140to perform input/output functions, etc. In one embodiment, peer platform370 is embedded into the operating system or firmware of peer 140.

Referring to FIG. 3, peer platform 370 can “publish” peer resources byplacing the resources, or a reference to these resources, in publicationdirectory 380. In one embodiment, publishing can be accomplished by theuser through an appropriate User Interface provided by platform 370 (notshown in FIG. 3). In one embodiment, publishing can be performed bypeer-to-peer applications 345 by calling the appropriate function in theAPI 340 of platform 370.

Other devices can browse the contents published by peer 140 byrequesting access to the top-level directory or directories published bythis peer 140, just like any other resource. Such requests, coming intopeer 140 as peer-to-peer traffic 320, may be the result of other usersbrowsing for content, or may be sent at the request of the RNS server,for instance, after a crash as part of a data recovery operation.

FIG. 4 illustrates another embodiment of locating a resource in moredetail, this time from the perspective of platform 370. A gate servermay perform similar functions. Other embodiments may not include all ofthe elements illustrated in FIG. 4, may perform elements in a differentorder, and may include additional elements.

Referring now to FIG. 4, when peer 140 generates a request for a networkor peer resource, either from peer-to-peer application 345 or Webbrowser 365, the proxy component 360 of platform 370 receives therequest at block 410.

At block 420, the proxy component 360 checks whether this is a requestfor peer-to-peer content. If it is determined that the request is for aregular network resource published on the Web or on the Intranet, theproxy component 360 just acts as a pass-through for the request, sendingthe request to the specified Web server or chaining with any existingproxy used by, or specified for, peer 140, as necessary. In oneembodiment, platform 370 makes this determination based on the format ofthe URL provided by peer 140. In another embodiment, platform 370 makesthis determination dynamically, as will be explained later under“Dynamic Peer-to-peer Realm Identification.” Assuming the request is aregular network resource, for instance having a URL including “www” fora World Wide Web page, the request is forwarded in 425 as regularnetwork traffic 325.

If, however, the request is for a peer resource, for instance having aURL including “ppp” or “rns”, the platform determines whether or not theaddressed locator service is known in 430. That is, platform 370 mayneed certain contact information for contacting the locator service forthe realm under which the peer resource has been published, which may ormay not be the same realm under which peer 140 has been registered. Forinstance, platform 370 may need to know the IP address and IP portnumber for the locator service.

If the locator service is known, the request is directed in 440 asresource locator traffic 310 to the home RNS server 130 to which thepeer 140 has been homed during the registration process, as describedearlier. The home RNS server 130 then follows the steps earlierdescribed in FIG. 2 to locate content published under its realm, or tocontact the remote locator service to locate a remote peer resource.

If the locator service is not known, platform 370 first tries to obtainand cache the needed contact information in 435. In one embodiment,platform 370 sends a request for the contact information to the locatorservice as regular network traffic 325. The locator service's gateserver 120 will receive and process the request. The request can simplycontain the original peer resource address requested by peer 140.Alternately, platform 370 indicates in the request that it is apeer-to-peer platform and includes various kinds of information toenable the locator service to advantageously determine compatibility. Ifthe gate service responds with the needed information, platform 370 cancache the information in cache 385 to avoid having to ask for theinformation again in the future; following this, platform 370 proceedsto forward the request to its home RNS server in 440, including theobtained contact information for the remote locator. If in 435 thelocator service is determined not to exist or does not respond, platform370 cannot forward the request in 440, but instead skips through 440 and445 to return an appropriate error message in 450.

If the request was forwarded in 440, platform 370 waits in 445 for aresponse from its home RNS server and checks to see if one or morelocations for the resource have been received. If no locations arereceived, platform 370 returns an appropriate error message in 450. Ifone or more locations are received, platform 370 selects one or morelocations to try in 460. The request is then forwarded as peer-to-peertraffic 320 directly to the selected location or locations in 425. Inone embodiment, if the location or locations selected by the client arenot available or do not contain the resource, platform 370 couldcontinue trying other locations that were returned in block 445 by thelocator service. In one embodiment, if multiple locations are availableand able to serve the resource, platform 370 may decide to stripe thefetching of the resource across multiple locations. Platform 370 may useany number of approaches to determine which location to try first. If alocation proves to be non-responsive, platform 370 can select anotherlocation for the resource from those locations previously cached.

For types of resources that can be copied, once the resource has beensuccessfully accessed, platform 370 has the option to cache a copy of aresource in its cache 385, and thus become a caching publisher for thatresource. In which case, platform 370 will also inform its home RNSserver via its resource locator interface 330 that it now has become acaching publisher for the resource. The home RNS server will then addthe location of the peer to its list of locations for the resource.Future requests for the resource from this peer or from other peers canbe directed by the home RNS server to this peer 140 and be serviced outof cache 385.

In addition to receiving requests from peer 140, platform 370 may alsoreceive requests for the cached resource in the form of resource locatortraffic 310 and/or peer-to-peer traffic 320. These requests cansimilarly be serviced out of cache 385.

In the embodiment illustrated in FIGS. 3 and 4, a separate protocol isused for peer-to-peer traffic 320 and regular network traffic 325, onthe one hand, and for resource locator traffic 310, on the other. Sincemessages exchanged during resource location are of a more specificnature than regular network traffic 325 or peer-to-peer traffic 320, theprotocol for the resource locator traffic 310 can be made more concise.For instance, rather than using a text-based protocol such as HTTP, theplatform 370 could communicate with its home RNS server by using a morebandwidth-efficient binary encoding of messages. These bandwidth savingscan be advantageously used to increase the number of peers 140 homed atthe same RNS server 130. In alternate embodiments, a single protocolcould be used for all types of traffic.

Gate Server

As mentioned above, gate server 120 from FIG. 1 performs some functionssimilar to those of RNS servers 130 described in FIG. 2 and peerplatform 370 described in FIG. 3. That is, if gate server 120 receives arequest for a peer resource in the form of a resource address, as peerplatform 370 does, gate server 120 takes steps to convert the access tothe resource to an appropriate peer-to-peer form.

For a compatible peer device that is requesting the resource, gateserver 120 may provide contact information so that the peer's platformcan directly send a peer request. In this case, gate server 120 cansimply inform the requester that this is a request to a peer resourcethat requires the requester to contact its home RNS server. A compatiblerequester is one that will be able to interpret the response from thegate server, then use its home RNS server to resolve the resourcelocation(s), and directly access the provided location(s).

For a non-compatible device, gate server 120 may itself convert therequest to peer form and act as a proxy on behalf of the requestingdevice. In this case, gate server 120 first processes the request muchlike platform 370 does, and then takes the extra step of accessing theresource on behalf of the requester. That is, if the requester isrequesting a copy of a file, the gate server can access a resource,download the file, and forward it to the requester. In this lastrespect, gate server 120 also performs some functions similar to peers140 in that the gate server actually accesses the resource.

Peer-to-peer Resource Addressing Scheme

As discussed above, the RNS addressing scheme is an important part ofthe RNS locator service. In one embodiment, the RNS addressing scheme isentirely compatible with the URL scheme that is currently used fornaming World Wide Web resources. That is, links between Web pages andpeer-to-peer resources are possible, and the transition from one kind ofresource to the other can be completely transparent to a user. Forinstance, a link in a web page has the same syntactic structure and canbe de-referenced by an unmodified Web browser, irrespective of whetherthe link connects to a traditional Web page or a peer-to-peer resource.

This embodiment of the RNS addressing scheme uses a hierarchical namingscheme similar to Universal Resource Locators (URLs). For instance, likeURLs, peer resource addresses can be of the following form:<access protocol>://<realm>/<peer>/<path>

Examples of access protocols include hypertext transfer protocol (HTTP),hypertext transfer protocol over an SSL (Secure Socket Layer) connection(HTTPS), file transfer protocol (FTP), and the like. The realmcorresponds to the peer-to-peer realm 150 under which the peer resourcehas been published, and is chosen to be identical to the DNS (DomainName Service) host name of the gate server 120 of that realm 150. Thusrealm names are unique in a networking environment just as domain namesare unique.

Following the realm in the illustrated embodiment is the peeridentifier. This corresponds to the peer identifier for the masterpublisher of a particular resource. As described earlier, peeridentifiers are assigned by a registrar 110 to be unique within a realm150.

Resources can be further organized into any number of levels ofhierarchy based, for instance, on path names for resources within apeer.

Dynamic Peer-to-peer Realm Identification

In one embodiment, a peer-to-peer resource address conformssyntactically to a regular Web URL and cannot be distinguished from aWeb URL by any syntactical conventions. Instead, a resource address isdynamically recognized as such when the address is de-referenced. Thisprovides a great deal of flexibility in naming realms. For instance, asdiscussed above in the embodiment of FIG. 1, external network traffic125 is received by gate server 120. Gate server 120 can resolve resourceaddresses and instruct the senders on how to query the resource locator,or gate server 120 can resolve resource addresses and access theresources on behalf of the senders.

FIG. 6 illustrates one embodiment of resolving a resource address fromthe perspective of a gate server.

At 610, the gate server receives a resource address as a regular WebURL.

At 620, if the requester is a compatible peer device, the gate serverinstructs the requester in 630 to use its own resource locator serviceto access the resource. In one embodiment, the gate server may be ableto recognize that the requester is a peer device based on a special HTTPheader included in the request by the requester. For instance, this canbe a “Via” header that specifies the type of the requester as“compatible peer device”. Alternately, the requester and the gate servermay exchange additional messages to confirm compatibility. If therequester is a compatible peer device, the requester may cache the realmname to avoid sending resource addresses to the gate server in thefuture.

If the requester is not a peer device in 620, the gate server obtainsthe requested content and returns it to the requester in 640.

Resource Coherence

For resources that can be cached in multiple locations and that canchange over time, cache coherency can be important. That is, if aresource is cached by multiple peers and then the master publisherupdates the resource, it is important not to service requests usingoutdated cached data. “Coherent cache” means that valid cached copies ofresources are equivalent to the master resource.

Depending on the type of resource, outdated data may or may not be aproblem. For example, if the resource is an amateur “joke of the day”website, users may not care if cached data is a couple of days old. Onthe other hand, if the resource is stock ticker data on a day traderwebsite, users will require fast updates. That is, higher priority datais likely to require more stringent cache coherency standards.

In order to account for multiple updates to a resource that maintainsthe same resource address, resource identifiers are used. A resourceidentifier for a given resource contains the resource address, as wellas a resource version number. In one embodiment, resource identifiersare generated by platform 370, as follows: the resource address isgenerated as a combination of the realm under which the peer 140 hasbeen registered, the peer's identifier, and the relative file systempath of the published resource in the peer's publication directory 380;the resource version number is based on the last creation ormodification time of that resource, as determined by peer-to-peerplatform 370 by examining its publication directory 380.

Each time a master publisher creates or modifies a resource, the masterpublisher generates a new resource version number based on the date andtime of the latest creation or modification of the resource.

In one embodiment, to ensure that resource version numbers are notinfluenced by variations in clock settings on peer machines, peers aresynchronized to a central realm clock. Clock synchronization can beaccomplished, for instance, when a peer machine comes on-line andinforms its RNS server of the peer's current IP address. Furthermore, toensure that clock drift on peer machines does not influence versionnumbering, peers can be re-synchronized to the central clock on aregular basis. In an alternate embodiment, version numbers can begenerated sequentially by platform 370.

One approach to ensure highly coherent data is to enable only the masterpublisher to modify a resource and to require all requests to check thecurrent resource identifier with the master publisher before eachaccess. For instance, each time a resource is requested, the locatorserver queries the master publisher for the current version of theresource and returns the current version with a list of locations wherethe current version is expected to be found.

If a peer caches a resource and subsequently requests the resourceagain, even though a version of the resource is cached in the peer's owncache 385, the peer will not access the resource until the locatorservice returns the most recent version number and the peer has verifiedthat its cached copy is the same version. If the version has changed,the requesting peer discards the obsolete version from its cache andaccesses the new version of the resource from the list of sourcessupplied by the locator service.

If a peer 140 or the gate server 120 fetches a resource from a cachingpublisher, they can check to ensure that the version indication in theresource identifier matches the expected version that was returned as aresult of a resource locator request. If the peer 140 sees a differentversion than expected, this may be due to the caching publisher cachingan obsolete version of the resource. In this case, the peer 140 must tryany other locations returned by the RNS server as a result of thelocator request, or may elect to repeat the locator request altogether.

Proactively querying the master publisher can create a tremendous amountof data traffic for the master publisher. For instance, in a realmhaving millions of peers, if the master publisher for a resource is adesktop computer coupled to the network by a regular 56K modem, themaster publisher could easily become a bottleneck for locator servicetraffic, even if locator service traffic uses a streamlined format.

A less problematic, yet somewhat lower level of coherency relies on themaster publisher to report changes and/or modifications rather thanproactively querying the master publisher for current versions. Forinstance, each time the master publisher publishes an updated version,the master publisher informs its home RNS server of the change. That is,the master publisher informs its home RNS server of the new resourceidentifier associated with the resource. If the RNS server has notreceived a notification from the master publisher, the RNS serverassumes its current record for the requested resource is accurate. Thiswas the case in the embodiment of FIG. 2.

The RNS server is likely to be running on a more robust machine, with amuch higher bandwidth data connection for locator service traffic, thanthat of the master publisher. In which case, requests could be servicedby the RNS server prior to accessing a resource with a much lowerlikelihood of creating a bottleneck. Still, in a very large peer-to-peerrealm, there is the possibility that a single home RNS server couldbecome a bottleneck. Or, at the very least, this approach could consumea great deal of bandwidth that might better be spent elsewhere.

Rather than always requiring the verification of version numbers from ahome RNS server or master publisher, another approach is to simply flushcaches from time to time. If an RNS server currently has a record for aresource, the RNS server uses the record. If a peer has a cached copy ofa resource, the peer uses the cached copy. The life span of a cacheditem can be adjusted based on the priority of the resource. Higherpriority items can be flushed more often.

If authority to modify a resource is not limited to one master user,cache coherency is possible, but it can require a great deal moreoverhead. For instance, if a number of users cache a resource andcollaboratively modify it, each new version created by each user couldbe broadcasted to all the other users, assuming the RNS servers trackedevery location where the resource had been cached.

Any number of alternate approaches can be used for cache coherency,including combinations of the approaches described above. In certainembodiments, users have the option to select the level of cachecoherency desired for various resources.

FIG. 5 illustrates one embodiment of a cache coherency scheme for aparticular record from the perspective of an RNS server. In theillustrated embodiment, a peer homed at the RNS server has previouslyaccessed and cached a resource. The RNS server then cached a resourcerecord listing the peer as a caching publisher for the resource, andalso listing the resource identifier (including version indication) forthe resource cached by the peer. The peer may be just one location amonga list of several locations at which the resource is expected to beavailable.

At 510, the RNS server watches for a request for the cached record.While waiting, the RNS server watches to see if the cached record hastimed out in 520. That is, the record has a time limit on how long theRNS server will cache it. If time has run out, the record is flushed in540 and the process ends. The time limit may apply to the entire recordreferring to all the locations for a particular resource, or the timelimit may only apply the caching publisher's location. If only thelocation of the caching publisher is flushed in 540, more recentlycached locations for the resource may continue to be maintained in theresource record at the RNS server.

While waiting for a request for the cached record, the RNS server alsowatches to see if a local master has updated the resource in 530. Thatis, if the master publisher for the resource is also homed at this RNSserver, the master publisher will inform the RNS server when theresource is updated by sending the RNS server a new resource identifier.In which case, the RNS server flushes the entire record of locations forthe old version of the resource in 540.

In one embodiment, the master publisher can selectively inform its homeRNS server of resource updates by only sending its home RNS serverinformation about changed resources that had been previously looked upby the home RNS server (and for which the home RNS server thus has acached resource record).

In one embodiment, the home RNS server can also notify the masterpublisher whenever the home RNS server chooses to discard the cachedresource record for a resource. Following such a notification, themaster publisher can temporarily stop sending change notifications forthat resource to its home RNS server until, for instance, the resourceis again looked up on the master publisher by the home RNS server.

In another embodiment, the home RNS server can reply to changenotifications received from the master publisher after the cachedresource record has been deleted with a status indication indicating tothe master publisher that the master publisher may temporarily stopsending change notifications for that resource to its home RNS server,until the resource is again looked up on the master publisher by thehome RNS server.

While waiting for a resource to time out or to be updated by the masterpublisher, the RNS server also watches to see if the caching publisherhas flushed the resource in 535. If the peer no longer caches theresource, there is no reason to continue caching the peer's locationwith respect to the resource. In one embodiment, peer platforms notifytheir RNS servers when a new resource is created, when a resource ismodified, and when a resource is deleted. The RNS servers update theirrecords accordingly.

Back at 510, if a request for the cached record is received, the RNSserver provides the cached status at 550. Note that the RNS server didnot watch for resource modifications from a master publisher homed at adifferent RNS server. That is, in the illustrated embodiment, changes inthe status of resources published by master publishers homed at remoteRNS servers are ignored by the RNS server of FIG. 5. In other words, ifa resource record has not timed out, the record is presumed valid. Thisapproach can greatly reduce the amount of inter-RNS server traffic. Afairly high level of coherency can also be maintained by keeping thelifespan of records for remote master publishers short.

In alternate embodiments, any number of additional criteria can be usedto flush records. For instance, if an RNS server runs low on memoryspace, it can flush records. Then, when more memory is available, an RNSserver can re-create records by querying peers for the current status ofpublished resources.

Implementation And Alternate Embodiments

Peers, such as peers 140 in FIG. 1, can include a wide variety ofdevices. In one embodiment, the peers are end-user machines, such asdesk top computers, laptop computers, handheld devices, and the like. Apeer can act like a client to request access to a resource availableelsewhere in the networking environment, as well as act like a server toservice requests for a resource available at the peer. Resourcesavailable at a peer may include files, directories of available files,devices attached to the peer, Web services, Microsoft .NET services,application instances, particular users (such as chat participants), andthe like.

RNS locator service traffic requires only a small amount of data trafficcompared to the amount of data involved in actually accessing mostresources. In other words, a peer merely asks an RNS server where aresource can be found and then goes to that location or set of locationsto actually access the resource. This two step process makes the RNSnetwork exceptionally “scalable,” which means it can support a vastnumber of peers and can grow rapidly without significant difficulty. Forinstance, since the first step uses very little data, the RNS serverscan handle a very large number of these small requests per time unit.The bulk of the data traffic is exchanged directly among the peers.Adding capacity is as easy as adding more RNS servers and registeringmore peers.

In FIG. 1, the elements in realm 150 communicate with one another usingany of a variety of network transmission protocols, such as the UserDatagram Protocol (UDP) or the Transmission Control Protocol (TCP), andany of a variety of application protocols, such as a proprietaryprotocol, the Hypertext Transfer Protocol (HTTP), the File TransferProtocol (FTP), or the like. The networking environment including realm150 may comprise a local area network (LAN), a wide area network (WAN),a private internet, the public Internet, or the like. In alternateembodiments, realm 150 may comprise a standalone network.

The RNS service can use any number of security measures, includingencryption, firewalls, and the like. A variety of protocol tools canalso be used to accommodate unreliable networking environments wherepackets can be lost, can be received out-of-order, can be duplicated,etc. For instance, requests and responses can be pipelined and/or sentmultiple times. Each transaction can include a “nonce,” which is aunique identifier generated by the initiator of a transaction todistinguish among multiple replies to the same request.

FIG. 7 illustrates one embodiment of a hardware system 700 intended torepresent a broad category of computer systems such as personalcomputers, workstations, and/or embedded systems. In the illustratedembodiment, the hardware system 700 includes processor 710 coupled tohigh speed bus 705, which is coupled to input/output (I/O) bus 715through bus bridge 730. Temporary memory 720 is coupled to bus 705.Permanent memory 740 is coupled to bus 715. I/O device(s) 750 is alsocoupled to bus 715. I/O device(s) 750 may include a display device, akeyboard, one or more external network interfaces, etc.

Certain embodiments may include additional components, may not requireall of the above components, or may combine one or more components. Forinstance, temporary memory 720 may be on-chip with processor 710.Alternately, permanent memory 740 may be eliminated and temporary memory720 may be replaced with an electrically erasable programmable read onlymemory (EEPROM), wherein software routines are executed in place fromthe EEPROM. Some implementations may employ a single bus, to which allof the components are coupled, or one or more additional buses and busbridges to which various additional components can be coupled. Thoseskilled in the art will be familiar with a variety of alternate internalnetworks including, for instance, an internal network based on a highspeed system bus with a memory controller hub and an I/O controller hub.Additional components may include additional processors, a CD ROM drive,additional memories, and other peripheral components known in the art.

In one embodiment, the present invention, as described above, isimplemented using one or more hardware systems such as the hardwaresystem 700 of FIG. 7. Where more than one computer is used, the systemscan be coupled to communicate over an external network, such as a localarea network (LAN), an internet protocol (IP) network, etc. In oneembodiment, the present invention is implemented as software routinesexecuted by one or more execution units within the computer(s). For agiven computer, the software routines can be stored on a storage device,such as permanent memory 740.

Alternately, as shown in FIG. 8, the software routines can be machineexecutable instructions 810 stored using any machine readable storagemedium 820, such as a diskette, CD-ROM, magnetic tape, digital video orversatile disk (DVD), laser disk, ROM, Flash memory, etc. The series ofinstructions need not be stored locally, and could be received from aremote storage device, such as a server on a network, a CD ROM device, afloppy disk, etc., through, for instance, I/O device(s) 750 of FIG. 7.

From whatever source, the instructions may be copied from the storagedevice into temporary memory 720 and then accessed and executed byprocessor 710. In one implementation, these software routines arewritten in the C programming language. It is to be appreciated, however,that these routines may be implemented in any of a wide variety ofprogramming languages.

In alternate embodiments, the present invention is implemented indiscrete hardware or firmware. For example, one or more applicationspecific integrated circuits (ASICs) could be programmed with one ormore of the above described functions of the present invention. Inanother example, one or more functions of the present invention could beimplemented in one or more ASICs on additional circuit boards and thecircuit boards could be inserted into the computer(s) described above.In another example, field programmable gate arrays (FPGAs) or staticprogrammable gate arrays (SPGA) could be used to implement one or morefunctions of the present invention. In yet another example, acombination of hardware and software could be used to implement one ormore functions of the present invention.

Thus, a Resource Naming Service is described. Whereas many alterationsand modifications of the present invention will be comprehended by aperson skilled in the art after having read the foregoing description,it is to be understood that the particular embodiments shown anddescribed by way of illustration are in no way intended to be consideredlimiting. Therefore, references to details of particular embodiments arenot intended to limit the scope of the claims.

1. A method performed by a resource naming system (RNS) server providingresource naming service in a peer-to-peer networking environment havingdifferent groups of peers assigned to different RNS servers, the methodcomprising: receiving a peer resource request at the RNS server, saidpeer resource request having been sent by a peer platform through thepeer-to-peer networking environment that the peer platform isparticipating in, the peer resource request comprising a peer resourceidentifier identifying a peer resource available on the peer-to-peernetworking environment, tracking peers in the peer-to-peer networkingenvironment that are assigned to the RNS server to determine whetherthose peers are connected to the peer-to-peer networking environment andin accordance with the tracking storing respective statuses ofrespective peers, a status indicating whether its corresponding peer isconnected to the peer-to-peer networking environment; generating a peerresource response based on the peer resource identifier and the statusesof the peers assigned to the RNS server, where indicia of a peerassigned to the RNS server is included in the peer resource responsebased on whether the peer resource identified in the peer resourcerequest is available from the peers and based on whether the status ofthe peer indicates that the peer is connected to the peer-to-peernetworking environment; and returning the peer resource response to thepeer platform through the peer-to-peer networking environment, said peerresource response to enable the peer platform to access the peerresource within the peer-to-peer networking environment.
 2. The methodof claim 1 wherein the peer resource identifier comprises at least oneof a realm name for a peer-to-peer realm including the RNS server and apath name for the peer resource.
 3. The method of claim 2 wherein thepeer resource identifier includes both the realm name and the path name,the peer resource identifier being persistent and/or unique within thepeer-to-peer networking environment.
 4. The method of claim 1 whereinthe peer-to-peer networking environment comprises a local area network,a wide area network, a private internet, and/or a public Internet. 5.The method of claim 1 wherein the peer resource response comprises anindication of a current version of the peer resource.
 6. The method ofclaim 1 wherein generating the peer resource response comprises:determining that resource status information regarding the peer resourceis currently cached within the RNS server; and generating the peerresource response based on the cached resource status information. 7.The method of claim 6 wherein the resource status informationcorresponds to a peer resource assigned either to the RNS serverreceiving the peer resource request or to a remote RNS server.
 8. Themethod of claim 1 wherein generating the peer resource responsecomprises: determining that a master publisher peer of the peer resourceis assigned to the RNS server based on the peer resource request;requesting and receiving resource status information corresponding tothe peer resource from the master publisher peer of the peer resource;and generating the peer resource response based on the resource statusinformation corresponding to the peer resource.
 9. The method of claim 8wherein the RNS server has stored a list of the peers assigned to theRNS server, and wherein determining that the master publisher is homedat the RNS server comprises comparing the master publisher name to thelist of peers assigned to the RNS server.
 10. The method of claim 8further comprising: caching the resource status information within theRNS server.
 11. The method of claim 8 wherein the resource statusinformation comprises a version number for the master resource, andwherein generating the peer resource response based on the resourcestatus information comprises: comparing the version number from theresource status information to a version number for resource statusinformation cached within the RNS server; generating the peer resourceresponse based on the resource status information cached within the RNSserver if the version numbers match; and generating the peer resourceresponse based on the resource status information from the masterpublisher if the version numbers do not match.
 12. The method of claim 1wherein generating the peer resource response comprises: determiningthat master publisher status information corresponding to the peerresource is currently cached within the RNS server based on the peerresource request, said master publisher status information indicating anassigned RNS server for the master publisher of the peer resource;identifying a path name for the peer resource from the peer resourcerequest; requesting and receiving resource status informationcorresponding to the peer resource from the assigned RNS server based onthe master publisher status information and the path name; andgenerating the peer resource response based on the resource statusinformation.
 13. The method of claim 12 further comprising: caching theresource status information within the RNS server.
 14. The method ofclaim 1 wherein generating the peer resource response comprises:identifying a master publisher name from the peer resource identifier;requesting and receiving master publisher status informationcorresponding to the master publisher name from a master publisherregistrar, said master publisher status information indicating a homeRNS server for the master publisher of the peer resource correspondingto the master publisher name; identifying a path name for the peerresource from the peer resource request; requesting and receivingresource status information corresponding to the peer resource from thehome RNS server based on the master publisher status information and thepath name; and generating the peer resource response based on theresource status information.
 15. The method of claim 14 furthercomprising: caching the master publisher status information and/or theresource status information within the RNS server.
 16. The method ofclaim 1 wherein generating the peer resource response comprises:selecting a set of network addresses from a plurality of networkaddresses where the peer resource is expected to be available in thepeer-to-peer networking environment, said plurality of network addressesbeing cached in the RNS server, and where the indicia of the peerassigned to the RNS server comprises one of the network addresses; andincluding the set of network addresses in the peer resource response,said peer platform to select from among the set of network addresses toaccess the peer resource.
 17. The method of claim 16 wherein the set ofnetwork addresses is selected from the plurality of network addresses inresponse to successive peer resource requests in a fashion thatdistributes access loads across said plurality of network addresses. 18.The method of claim 17 wherein selecting the set of network addressesfrom the plurality of network addresses in response to successive peerresource requests comprises: comparing a network address for the peerplatform to each of the plurality of network addresses, said networkaddress for the peer platform being part of the peer resource request,and a degree of relatedness between any two network addresses suggestinga related degree of topological closeness within the peer-to-peernetworking environment; and selecting network addresses from among theplurality of network addresses that have a highest degree of relatednessto the network address for the peer platform.
 19. The method of claim 1,wherein the RNS server comprises a local RNS server, and the peerresource request comprises a first peer resource request, the methodfurther comprising: receiving a status request at the local RNS server,said status request corresponding to a local peer resource, and saidstatus request being received from a remote RNS server through thepeer-to-peer networking environment; generating a status response forthe local peer resource; and returning the status response to the remoteRNS server through the peer-to-peer networking environment, said statusresponse to enable the remote RNS server to service a peer resourcerequest for the local peer resource.
 20. The method of claim 19 whereinsaid status response comprises at least one of a current version for thelocal peer resource and zero or more network addresses for the localpeer resource.
 21. The method of 19 wherein the status request comprisesa realm name for a peer-to-peer realm including the RNS server, a uniquemaster publisher name corresponding to a master publisher of the localpeer resource, and/or a pathname for the local peer resource within themaster publisher.
 22. The method of claim 19 wherein a master publisherof the local peer resource is homed at the local RNS server.
 23. Themethod of claim 19 further comprising: caching the status responsewithin the remote RNS server, said remote RNS server to servicesubsequent peer resource quests for the local peer resource based on thecached status response.
 24. The method of claim 23 further comprising:flushing the status response from the remote RNS server after aparticular period of time.
 25. A machine readable storage medium havingstored thereon machine executable instructions to implement a methodcomprising: receiving a peer resource request at a resource namingservice (RNS) server, said peer resource request being received from apeer platform through a peer-to-peer networking environment, the peerresource request comprising a peer resource identifier identifying apeer resource; determining and storing statuses of peers in thepeer-to-peer networking environment that are assigned to the RNS server,the statuses indicating whether respective peers are available on thepeer-to-peer networking environment; generating a peer resource responsebased on the peer resource identifier and the determined statuses of thepeers, where addresses or identifiers of peers are assigned to the RNSserver are selected to be included in the peer resource response basedon their having the peer resource and based on their previously storedstatuses indicating whether they are available on the peer-to-peernetworking environment; and returning the peer resource response to thepeer platform through the peer-to-peer networking environment, said peerresource response to enable the peer platform to access the peerresource within the peer-to-peer networking environment.
 26. The machinereadable storage medium of claim 25 wherein the peer resource identifiercomprises a realm name for a peer-to-peer realm including the RNS serverand/or a path name for the peer resource.
 27. The machine readablestorage medium of claim 26 wherein the peer resource identifier includesboth the realm name and the path name, the peer resource identifierbeing persistent and/or unique within the networking environment. 28.The machine readable storage medium of claim 25 wherein the peer-to-peernetworking environment comprises a local area network, a wide areanetwork, a private internet, and the public Internet.
 29. The machinereadable storage medium of claim 25 wherein the peer resource responsecomprises an indication of a current version of the peer resource and/ora list of zero or more locations of peers within the peer-to-peernetworking environment where the peer resource is expected to beavailable.
 30. The machine readable storage medium of claim 25 whereingenerating the peer resource response comprises: determining thatresource status information regarding the peer resource is currentlycached within the RNS server; and generating the peer resource responsebased on the cached resource status information.
 31. The machinereadable storage medium of claim 30 wherein the resource statusinformation corresponds to a peer resource assigned either to the RNSserver receiving the peer resource request or to a remote RNS server.32. The machine readable storage medium of claim 25 wherein generatingthe peer resource response comprises: determining that a masterpublisher of the peer resource is homed at the RNS server based on thepeer resource request; requesting and receiving resource statusinformation corresponding to the peer resource from the master publisherof the peer resource; and generating the peer resource response based onthe resource status information corresponding to the peer resource. 33.The machine readable storage medium of claim 32 wherein the RNS serverhas stored a list of the peers assigned to the RNS server, and whereindetermining that the master publisher is homed to the RNS servercomprises comparing the master publisher name from the peer resourceidentifier to the list of peers assigned to the RNS server.
 34. Themachine readable storage medium of claim 32 the method furthercomprising: caching the resource status information within the RNSserver.
 35. The machine readable storage medium of claim 32 wherein theresource status information comprises a version number for the masterresource, and wherein generating the peer resource response based on theresource status information comprises: comparing the version number fromthe resource status information to a version number for resource statusinformation cached within the RNS server; generating the peer resourceresponse based on the resource status information cached within the RNSserver if the version numbers match; and generating the peer resourceresponse based on the resource status information from the masterpublisher if the version numbers do not match.
 36. The machine readablestorage medium of claim 25 wherein generating the peer resource responsecomprises: determining that master publisher status informationcorresponding to the peer resource is currently cached within the RNSserver based on the peer resource request, said master publisher statusinformation indicating an assigned RNS server for a master publisher ofthe peer resource; identifying a pathname for the peer resource from thepeer resource request; requesting and receiving resource statusinformation corresponding to the peer resource from the assigned RNSserver based on the master publisher status information and the pathname; and generating the peer resource response based on the resourcestatus information.
 37. The machine readable storage medium of claim 36,the method further comprising: caching the resource status informationwithin the RNS server.
 38. The machine readable storage medium of claim25 wherein generating the peer resource response comprises: identifyinga master publisher name from the peer resource identifier; requestingand receiving master publisher status information corresponding to themaster publisher name from a master publisher registrar, said masterpublisher status information indicating a home RNS for a masterpublisher of the peer resource corresponding to the master publishername; identifying a path name for the peer resource from the peerresource request; requesting and receiving resource status informationcorresponding to the peer resource from the home RNS server based on themaster publisher status information and the path name; and generatingthe peer resource response based on the resource status information. 39.The machine readable storage medium of claim 38, the method furthercomprising: caching the master publisher status information and/or theresource status information within the RNS server.
 40. The machinereadable storage medium of claim 25 wherein generating the peer resourceresponse comprises: selecting a set of network addresses from aplurality of network addresses where the peer resource is expected to beavailable in the peer-to-peer networking environment, said plurality ofnetwork addresses being cached in the RNS server; and including the setof network addresses in the peer resource response, said peer platformto select from among the set of network addresses to access the peerresource.
 41. The machine readable storage medium of claim 40 whereinthe set of network addresses is selected from the plurality of networkaddresses in response to successive peer resource requests in a fashionthat distributes access loads across said plurality of networkaddresses.
 42. The machine readable storage medium of claim 41 whereinselecting the set of network addresses from the plurality of networkaddresses in response to successive peer resource requests comprises:comparing a network address for the peer platform to each of theplurality of network addresses, said network address for the peerplatform being part of the peer resource request, and a degree ofrelatedness between any two network addresses suggesting a relateddegree of topological closeness within the peer-to-peer networkingenvironment; and selecting network addresses from among the plurality ofnetwork addresses that have a highest degree of relatedness to thenetwork address for the peer platform.
 43. The machine readable storagemedium of claim 25, wherein the RNS server comprises a local RNS server,and the peer resource request comprises a first peer resource request,the method further comprising: receiving a status request at the localRNS server, said status request corresponding to a local peer resource,and said status request being received from a remote RNS server throughthe peer-to-peer networking environment; generating a status responsefor the local peer resource; and returning the status response to theremote RNS server through the peer-to-peer networking environment, saidstatus response to enable the remote RNS server to service a peerresource request for the local peer resource.
 44. The machine readablestorage medium of claim 43 wherein said status response comprises acurrent version for the local peer resource and/or zero or more networkaddresses for the local peer resource.
 45. The machine readable storagemedium of claim 43 wherein the status request comprises a unique masterpublisher name corresponding to a master publisher of the local peerresource and/or a path name for the local peer resource within themaster publisher.
 46. The machine readable storage medium of claim 43wherein a master publisher of the local peer resource is homed at thelocal RNS server.
 47. The machine readable storage medium of claim 43,the method further comprising: caching the status response within theremote RNS server, said remote RNS server to service subsequent peerresource quests for the local peer resource based on the cached statusresponse.
 48. The machine readable storage medium of claim 47, themethod further comprising: flushing the status response from the remoteRNS server after a particular period of time.
 49. An apparatuscomprising: a resource naming service (RNS) server to receive a peerresource request, said peer resource request being received from a peerplatform through a peer-to-peer networking environment, the peerresource request comprising a peer resource identifier identifying apeer resource available on the peer-to-peer networking environment; saidRNS server to determine statuses of peers in the peer-to-peer networkingenvironment that are assigned the RNS server as a home RNS server, thestatuses indicating whether respective peers are connected to thepeer-to-peer network, where as peers connect or disconnect to thepeer-to-peer network their status changes accordingly; said RNS serverto generate a peer resource response based on the peer resource requestby identifying peers assigned to the RNS server that have cached orpublished the peer resource and that have statuses that indicate theyare connected to the peer-to-peer network; and said RNS server to returnthe peer resource response to the peer platform through the peer-to-peernetworking environment, said peer resource response to enable the peerplatform to access the peer resource within the peer-to-peer networkingenvironment.